Slots show up in the tree twice, once under the bone they are attached to and once under Draw Order. When you click an image, the image is selected in the tree. If you hide attachments in the tree with the filter button at the top, when you click an image, the slot is selected under the bone. If you hide bones in the tree with the filter button at the top, Draw Order is gone and Slots has the list of slots which are ordered by draw order and can be dragged. Now each slot only appears once in the tree. When you click an image, the slot is selected under Slots, which is what you wanted. 🙂
